HISTORY OFASTRONOMY
BY
GEORGE FORBES,
M.A., F.R.S., M. INST. C. E.,
M.A., F.R.S., M. INST. C. E.,
(FORMERLYPROFESSOR OF NATURAL PHILOSOPHY, ANDERSON’S COLLEGE, GLASGOW)
AUTHOROF “THE TRANSIT OF VENUS,” RENDU’S “THEORY OF THE GLACIERS OF SAVOY,” ETC.,ETC.
CONTENTS
Preface
BOOKI. THE GEOMETRICAL PERIOD
1. PrimitiveAstronomy and Astrology
2. Ancient Astronomy--Chinese and Chaldæans
3. Ancient GreekAstronomy
4. The Reign ofEpicycles--from Ptolemy to Copernicus
BOOKII. THE DYNAMICAL PERIOD
5. Discovery of theTrue Solar System--Tycho Brahe--Kepler
6. Galileo and TheTelescope--Notions of Gravity by Horrocks, etc.
7. Sir Isaac Newton--Lawof Universal Gravitation
8. Newton'sSuccessors--Halley, Euler, Lagrange, Laplace, etc.
9. Discovery of NewPlanets--Herschel, Piazzi, Adams, and LeVerrier
BOOK III. OBSERVATION
10. Instruments ofPrecision--Size of ote Solar System
11. History of theTelescope--Spectroscope
BOOK IV. THE PHYSICAL PERIOD
12. The Sun
13. The Moon and Planets
14. Comets and Meteors
15. The Stars and Nebulæ
INDEX
Anattempt has been made in these pages to trace the evolution of intellectualthought in the progress of astronomical discovery, and, by recognising thedifferent points of view of the different ages, to give due credit even to theancients. No one can expect, in a history of astronomy of limited size, to finda treatise on “practical” or on “theoretical astronomy,” nor a complete“descriptive astronomy,” and still less a book on “speculative astronomy.”Something of each of these is essential, however, for tracing the progress ofthought and knowledge which it is the object of this History to describe.
Theprogress of human knowledge is measured by the increased habit of looking atfacts from new points of view, as much as by the accumulation of facts. Themental capacity of one age does not seem to differ from that of other ages; butit is the imagination of new points of view that gives a wider scope to thatcapacity. And this is cumulative, and therefore progressive. Aristotle viewedthe solar system as a geometrical problem; Kepler and Newton converted thepoint of view into a dynamical one. Aristotle’s mental capacity to understandthe meaning of facts or to criticise a train of reasoning may have been equalto that of Kepler or Newton, but the point of view was different.
Then,again, new points of view are provided by the invention of new methods in thatsystem of logic which we call mathematics. All that mathematics can do is toassure us that a statement A is equivalent to statements B, C, D, or is one ofthe facts expressed by the statements B, C, D; so that we may know, if B, C,and D are true, then A is true. To many people our inability to understand allthat is contained in statements B, C, and D, without the cumbrous process of amathematical demonstration, proves the feebleness of the human mind as alogical machine. For it required the new point of view imagined by Newton’sanalysis to enable people to see that, so far as planetary orbits areconcerned, Kepler’s three laws (B, C, D) were identical with Newton’s law ofgravitation (A). No one recognises more than the mathematical astronomer thisfeebleness of the human intellect, and no one is more conscious of thelimitations of the logical process called mathematics, which even now has notsolved directly the problem of only three bodies.
Thesereflections, arising from the writing of this History, go to explain theinvariable humility of the great mathematical astronomers. Newton’s comparisonof himself to the child on the seashore applies to them all. As each newdiscovery opens up, it may be, boundless oceans for investigation, for wonder,and for admiration, the great astronomers, refusing to accept mere hypothesesas true, have founded upon these discoveries a science as exact in itsobservation of facts as in theories. So it is that these men, who have built upthe most sure and most solid of all the sciences, refuse to invite others tojoin them in vain speculation. The writer has, therefore, in this shortHistory, tried to follow that great master, Airy, whose pupil he was, and thekey to whose character was exactness and accuracy; and he recognises thatScience is impotent except in her own limited sphere.
Ithas been necessary to curtail many parts of the History in the attempt—perhapsa hopeless one—to lay before the reader in a limited space enough about eachage to illustrate its tone and spirit, the ideals of the workers, the gradualaddition of new points of view and of new means of investigation.
Itwould, indeed, be a pleasure to entertain the hope that these pages might,among new recruits, arouse an interest in the greatest of all the sciences, orthat those who have handled the theoretical or practical side might be led bythem to read in the original some of the classics of astronomy. Many studentshave much compassion for the schoolboy of to-day, who is not allowed the luxuryof learning the art of reasoning from him who still remains pre-eminently itsgreatest exponent, Euclid. These students pity also the man of to-morrow, whois not to be allowed to read, in the original Latin of the brilliant Kepler,how he was able—by observations taken from a moving platform, the earth, of thedirections of a moving object, Mars—to deduce the exact shape of the path ofeach of these planets, and their actual positions on these paths at any time.Kepler’s masterpiece is one of the most interesting books that was everwritten, combining wit, imagination, ingenuity, and certainty.
Lastly,it must be noted that, as a History of England cannot deal with the presentParliament, so also the unfinished researches and untested hypotheses of manywell-known astronomers of to-day cannot be included among the records of theHistory of Astronomy. The writer regrets the necessity that thus arises ofleaving without mention the names of many who are now making history inastronomical work.
G.F.
August1st, 1909.
